The field of the invention is optics, measuring and testing with optical pyrometers and the invention is particularly concerned with a method and apparatus to contactlessly measure the brake temperature of passing railroad cars.
The state of the art of measuring the temperature of the running gear of railway cars may be ascertained by reference to U.S. Pat. No. 3,998,549 and Canadian Patent No. 1,197,300 the disclosures of which are incorporated herein by reference.
U.S. Pat. No. 3,998,549 and the references disclosed therein disclose how to measure the temperature of the brakes or of the wheel flanges of passing railroad cars by detecting the infrared (IR) heat rays emitted by the brakes.
It is further known from U.S. Pat. No. 3,151,827 to mount switch means on tracks which when passed by a wheel shall emit a gating pulse whereby the measuring system is activated and deactivated when a wheel enters and leaves the measuring zone. Such measuring systems consist in known manner of an optics followed by an IR sensor jointly defining a measuring axis.
In the past the railroad car brakes all were of approximately the same design, namely shoe brakes, and therefore it was possible to measure all brakes or wheel flanges with a single type of measuring system.
In the course of time however the most diverse brake systems and geometries have been developed, so that presently it is no longer practically possible to reliably detect all brake geometries possibly present in a train by means of a single measuring system specifically associated with a given wheel. Illustratively such diverse brake systems can be: the conventional shoe brakes wherein the shoes act on the periphery of the wheel tread, further outer or inner disk brakes wherein the wheel itself is the disk, and lastly high-performance inner disk brakes, wherein one or more separate disks are fixed between the wheels on the axle.
Furthermore, railroad car wheels assume the most diverse diameters and axle spacings.